1. Field of the Invention
The present invention relates to a method for assigning a transmission-equipment identification number in a transmission system and to transmission equipment that realizes the method.
2. Description of the Related Art
In a transmission system such as one using optical communications, which is used for transmission between remote locations, repeaters are provided on a transmission path in most cases.
FIG. 2 shows an example of such a system having repeaters, wherein a plurality of repeaters 21, 22, 23 (in this drawing, only three) are interposed between terminal equipment 10 and 11 facing each other and transmission system managing equipment 30, 31 are provided in one or both of the pieces of terminal equipment 10, 11 (each component can be referred to as a "device" hereinafter.)
Each piece of transmission system managing equipment 30, 31 is provided to constantly monitor, by using a monitor line, whether there is any failure in the terminal equipment (10 or 11) or in the repeater (21, 22, or 23), so as to maintain a safe operation of the transmission system. This monitoring operation is performed in such a manner that a signal on a system monitor line (which will be hereinafter referred to as a monitor signal) independent of signals on subscribers' lines (each of which will be hereinafter referred to as a main signal) accommodated in the terminal equipment (10 or 11) are transmitted and received between the transmission system managing equipment (30 or 31) and either the terminal equipment (10 or 11) or the repeater (21, 22, or 23) to be monitored.
Here, transmission equipment to be monitored (the terminal equipment 10 or 11, or the repeater 21, 22, or 23) is specified by a device identification number (which will be hereinafter referred to as an ID) assigned to each device to be monitored, which is included in a monitor signal.
Conventionally, the ID is set manually by an operator at the time of installation of each transmission equipment with an ID setting switch such as a DIP switch being provided in the transmission equipment.
However, a conventional method for assigning a transmission-equipment identification number has the following problems:
(1) Prior to installation of a transmission system, it is necessary for an operator to determine IDs without causing any duplication for all the devices in the system. For this reason, when there is a large number of pieces of transmission equipment, there is a possibility that the same ID is mistakenly assigned to different pieces of transmission equipment.
(2) When a setting error or a failure in setting occurs, a supervisory function of the transmission system cannot operate effectively. Therefore, in this case, the operator is forced to go to a position where the transmission equipment is installed and to perform the setting process again.
(3) It is necessary to determine IDs without duplication, whenever a repeater or the like is newly added to or removed from the transmission system. Further, when the ID of transmission equipment other than the transmission equipment newly added or removed is altered, it is also necessary for the operator to perform setting process at a position where the transmission equipment is installed.
In view of the aforementioned, a method for assigning a transmission-equipment identification number and transmission equipment are required, which allow assignment of an ID to each transmission equipment without using an ID setting switch.